1. Field of the Invention
This invention relates generally to the field of road line detection systems, and, more particularly, to road line detection systems which can distinguish lane markings for a vehicle to follow.
2. Related Art
Many industries, including the automotive industry, are utilizing advanced automation capabilities. The opportunity exists to automate many of the functions of a traditional vehicle. Some research is being performed in the automotive industry to make a vehicle completely autonomous; requiring no human input at all.
Several benefits exist as the result of vehicles becoming more automated or completely autonomous. Benefits include reduced traffic accidents, improved traffic flow, and reduced fuel consumption, just to name a few. For example, many vehicles are utilizing collision avoidance technology where the vehicle's computer system can apply the brakes if the vehicle's sensors detect that the vehicle is in danger of colliding with another vehicle or object. Also, many vehicles have introduced a parallel parking feature which allows the vehicle to parallel park without any input from the driver of the vehicle.
The plausibility of automated or autonomous vehicles is heavily dependent on the ability of the vehicle sensors and the vehicle computer system to identify and process the vehicle's environment and to react to different situations in a safe and efficient manner. However, the vehicle environment is very dynamic. Thus, the vehicle computer system needs to be able to perform in varying weather conditions, such as, rain or snow, and react to various road conditions, such as, icy roads or roads that are under construction. The challenge exists to guarantee a safe and efficient driving experience, regardless of the vehicle environment.
Some vehicle automation techniques used for vehicle navigation consider the painted lane markings on the surface of a road. The lane markings can be used as a means to safely guide the vehicle along its route. However, at least a few difficulties arise from the use of lane markings. For example, road surface markings not only include lane markings, but they also include navigation information, such as, turning lane indicators, speed limit information, crosswalk information, railroad information, and high-occupancy vehicle (HOV) markings. Distinguishing between lane markings and other road surface markings can be difficult.
Another challenge is distinguishing between ambiguous lane markers that can occur, for example, during road construction, maintenance, or upgrades. Lanes can be shifted to one side or another during periods of construction to facilitate the maintenance of roads. During the period of construction road maintenance, or upgrades, new lane markings are painted onto the road and old lane markings can either be scraped away or painted in the color of the road in an effort to mask the old lane markings. However, masking attempts are not always fully successful and old lane markings can sometimes be seen after scraping or re-painting. As such, conditions may exist where two sets of lane markings can be seen for a particular lane of the road. Determining which set of lane markings to follow in an automated manner can be difficult.